The present invention relates to a belt for a track-driven vehicle, such as a snowmobile.
Track belts provided on motor driven vehicles, such as snowmobiles, usually comprise a body made of elastomeric material. This body has an outer surface which contacts the ground and an inner surface which cooperates with a slide suspension system and a driving system. Generally, the body is driven by one of several driving wheels, such as sprocket wheels, which engage openings or driving lugs provided on the inner surface of the track belt. The slide suspension system is designed for supporting the chassis of the vehicle and usually comprises a pair of parallel slide rails contacting the inner surface of the track belt. Such rails also support the track belt with respect to lateral movements.
Formerly, each slide rail of a slide suspension system was aligned with a corresponding row of openings designed for engagement with teeth of a corresponding sprocket wheel. Such positioning of the slide rails reduces the portion of the inner surface of the track belt that is in contact with the slide rails and thus the amount of friction therebetween. It was found that, eventhough the friction was reduced, failures and rapid wear of the track belt and slide rails were still observed. To overcome this drawback, in U.S. Pat. No. 3,887,243 (Chaumont), the portions of the inner surface contacting the slide rails were provided with metal clips to reduce friction occurring between the inner surface of the body and the slide rails. It is also well known in the prior art that, in order to minimize friction between the inner surface of the track belt and the slide rails and also to facilitate the positioning of the clips, the slide rails were positioned above a corresponding pathway of clips essentially separated from each other by a hole.
It is also known in the art that, to maintain a sufficient sturdiness of the track belt, it is advantageous to have a maximum amount of clips. However, this increases the weight of the track belt. Therefore, there is a strong need for a track belt that does not have the drawback of those of the prior art with respect to friction existing between the inner surface of the track belt and the slide rails while reducing the whole weight of the track belt.
Therefore, the prior art teaches to the man skilled in the art that slide rails must contact a maximum of frictionless clips and a minimum of the inner surface of the track belt.
An object of the invention is to embody a track belt for motor vehicles, such as snowmobiles, having to cooperate with slide rails of a slide suspension system, which shows at once high characteristics of strength, resistance and durability, avoids friction between its inner surface and the slide rails and has a reduced weight with respect to track belts already known in the art.
Another object of the present invention is to enable the formation of a lubricating effect between the slide rails and the inner surface of the track belt in order to achieve this friction reduction.
Another object of the invention concerns a method for making a snowmobile track with a view to minimizing friction between the slide rails and the corresponding inner surface of the track belt.
However, contrary to the teachings of the prior art, the applicant has surprisingly found that it is possible to have a substantial portion of the inner surface in contact with slide rails, while still limiting the friction existing between them. More particularly, the applicant has discovered an improvement in an endless track belt of the type comprising a body made of an elastomeric material, the body having an outer surface for contact with the ground and an inner surface provided with means for engagement with driving means. The inner surface is also provided with at least one endless pathway having a sliding surface contacting a corresponding slide rail of a slide rail suspension. The elastomeric material of the track belt is composed of rubber and a lubrication means so that, at the sliding contact of the inner surface of the track belt, friction is greatly reduced due to the presence of such lubrication.
In one preferred form of the invention, this composition of rubber material and lubricating means is provided only in the endless pathway of the track which contacts the slide rail of the sliding rail suspension.
In another form of the invention, the complete inner surface of the track belt is composed of a layer of rubber and lubricating means.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that this detailed description, while indicating preferred embodiments of the invention, is given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art.